Gasket



GASKET Original Filed June 11, 1932 Fig.1

mmgga E. E. HEWITT ll Lo 2 Sheets-Sheet 1 ll ""iin.

P 1937. E. E. HEWITT 2,092,393

GASKET Original Filed June 11, 1932 V 2 Sheets-Sheet 2 INVENTOR ELLIS E.HEWITT 57 ATTORNEY Patented Sept. 7, 1937 UNITED STATES PATENT OFFiCEWestinghouse Air Brak e Company, Wilmerding, Pa., a corporation ofPennsylvania Original application June 11, 1932, Serial No.

616,681, now Patent No. 2,055,103. Divided and this application November27, 1935, Serial No.

1 Claim.

This invention relates to gaskets, particularly askets ior sealing ajoint between two cooperating metal members, such as the cylinder casingand cover of a fluid pressure brake controlling valve device, thepresent application being a division of my copending application, SerialNo. 616,681, now Patent No. 2,055,103, filed June 11, 1932, and assignedto the assignee of this application.

An object of the invention is to provide a one piece gasket constitutinga combined gasket and flexible diaphragm that may be eifectively used toseal the joint between two casing members having'metal to metal contact,and which may be confined in a groove or recess in'a. face of one of themetal members.

' A further object of the invention is to provide a casing structure anda gasket structure therefor having the abovenoted characteristics,wherein the metal engaging marginal portions of the gaskatsare made ofrelatively hard yielding material, such as rubber or composition, andthe diaphragm portion thereof is made of relatively soft flexiblematerial, such as rubber integrally joined ,to the harder marginalportion, and wherein the marginal portion of the gasket structure isprovided with sealing ribs adapted to be pressed into the body of thestructure by the casing for effecting a tight seal between the membersof the casing structure. I

A further object of the invention is to provide a gasket havingintegrally joined relatively hard and soft portions and a simple andinexpensive method of producing the gasket.

These and other objects of the invention tha will be made apparentthrough the further description thereof, are attained by means of-thecasing and gasket structures and the method of making the gasketstructure hereinafter described and illustrated in the accompanyingdrawings; wherein Fig. l is a sectional view of a casing structure andgasket structure taken on the line ll of Fig. 2 and embodying featuresof the invention.

Fig. 2 is an elevational view of a head or cover member of the casingstructure shown in Fig. 1, with an improved gasket structure mountedtherein.

Fig. 3 is a sectional view of a fragment of the structure shown in Fig.2, the section being taken on the line 3--3 of Fig. 2.

Fig. 4 is an elevational view of an improved gasket structure embodyingfeatures of the invention.

(Gl. ass-1) a Fig. 4.

Fig. 6 is an elevational view showing the blanks and their arrangementprior to the molding andspectively, that are drawn into metal to metalcontact by means of a plurality of bolts [6, one of which is shown.

As indicated in Figs. 1 and 2, the cover or head I 3 is provided with arecess ll of irregular contour and having a-flat bottom face, which isadapted to support the inner face of the gasket structure I I.

extend beyond the contact face l and into a chamber 2| and a shallowrecess 22, respectively, in the casing l2 as indicated in Fig. 1. Theprojection l9 surrounds a chamber 23 in the cover or head l3 and snuglyfits within the recess 22 and serves as a centering member for properlycentering the head member upon the casing 12 during the assemblyoperation. The circular walls 24 and 25 of the projections l8 and 19constitute confining walls for the portions of the gasket surroundingthe openings 26 and 21 in the .gasket structure ll, Fig. 4.

By reference to Fig. 4 it will be seen that the gasket structure llcomprises a plurality of an-.- nular portions28, 29 and 3| and acircular portion 32, integrally joined to constitute a single one piececombined gasket and diaphragm structure', the annular portions 28, 29and 31 and the marginal portion 33 of the circular diaphragm portion 32being adapted to be clamped between the casing and cover members I2 andi 3 respectively, for sealing the joint between said members.

The annular portions 28, 29 and 3i andthe marginal portion 33 of thediaphragm portion 32 are made of relatively hard yielding material, suchas semi-hard rubber, and the said portions are provided with circularsealing ribs 34 disposed as shown in Figs. 2 and 4 and which extendabove the flat surface of the gasket structure, and when the gasketstructure is in oper- The cover or head I3 is also proj vided withcircular projections l8 and I9 that 5 is a section taken on the line 5 5of to metal contact with the casing l2 as indicated in Fig. l, the ribsare pressed into the body of the gasket structure. Rubber or compositionis substantially incompressible and consequently when the contact ribs34 are pressed inwardly by the contact face l4 of the casing structurel2 with which they are engaged, the material in the body of the gasketstructure which is conflned between the outer side walls of the recessl1 and the circular walls -24 and 25 of the prol5 J'ections l8 and I9,flows outwardly toward the contact face H of the casing l2. For thisreason, the thickness of the gasket structure is made less than thedepth of the recess |1, thereby providing a space 35 between the outerfaceof the 20 gasket and the contact face H of the casing member intowhich the material of the gasket may flow, when the sealing ribs 34 arepressed into the body of the gasket structure. Relatively great pressureis required to press the sealing ribs 25 34 into the body of thestructure and consequently an effective seal is effected.

It has been found that fluid-tight joints without gaskets may beproduced by a metal to metal contact of the casing and cover members but0 unless the surfaces are carefully machined and ground, slight leakageis liable to occur. A metal to metal joint, however, in certain cases ishighly desirable, as in the present instance, for insuring that the headbe disposed in a. predetermined 35 position with respect to the casingin order that a predetermined volume be maintained in the chamber closedby the head. Where a gasket alone is relied 'upon to seal the jointbetween the casing and the cover, the position of the cover 40 isdependent upon the degree of compression of the gasket. Furthermore, ithas been found that where the cover is drawn tightly into contact withthe body of the gasket in the endeavor to obtain a fluid-tight seal, thegasket is liable to 45 flow and squeeze out of the space between thecasing and the cover, and in the case where a diaphragm is clampedbetween the metal members, the diaphragm is distorted by the flow ofgasket material from between the contacting sur- 5 faces of the metalmembers.

Heretofore, where metal to metal contacts were employed to provide afluid-tight joint, it was not practical to use a yielding packingmaterial where it would be confined as in the present instance 5 becauseof the liability of the packing material to flow into the space betweenthe contacting surfaces while the casing parts are being drawn together,thereby preventing actual metal to metal contact of the parts andimproper sealing of 0 the cover upon the casing. By using a gasket, thethickness of which is less than the depth of the groove in which it ismounted, and having sealing ribs thereon which are adapted to becompressed into the body of the gasket structure,

5 spaces are provided for the flow of the gasket material as the sealingribs are pressed into the body of the gasket structure and consequentlythe gasket cannot interfere with the proper positioning of the coverupon the casing in metal to 70 metal contact. A double seal is,therefore, pro- 75 desirable in case of a diaphragm constituting Thus amore eflicient seal is part of the sealing gasket. It has been foundthat compression of the marginal portion of the usual diaphragm betweentwo metal surfaces causes the material of the margin to flow toward thecenter or toward the diaphragm and to cause it to buckle. By usingsealing ribs as described above, the flow is localized in the vicinityof the sealing ribs and confined to the space between the gasket and thecontact faces of the metal member. Consequently there is no tendency forthe material in the margin of the diaphragm to flow radially inwardlyand cause distortion of the diaphragm.

In order to obtain an effective seal, it has been found that the marginof the gasket that is clamped between the metal members should be.

made of material that is relatively hard, but which will yield when themetal parts are drawn into engagement. This material does not havesufllcient flexibility for use as a diaphragm. Accordingly, thediaphragm portion of the gasket is made of a soft rubber of the requiredflexibility, which is joined integrally to the relatively hard marginalportion 33 during the vulcanizing operation while forming the gasketwithin a suitable mold.

By reference to Fig. 5, it will be seen that the diaphragm portion 32 ofthe gasket structure comprises a central portion 36 that is made ofrelatively soft flexible rubber in which the reinforcing fabric 31 isembedded. The outer face of the marginal portion 33 of thediaphragmportion 32 is made of substantially the same material as theannular portions 28, 29 and 3| of the gasket structure. Thus the outercontacting face of the entire gasket structure is of relatively hardmaterial and the sealing ribs 34 are composed of the same hard material.

The gasket structure is manufactured by the following method:

A blank 4|, having the general shape and contour of the annular portions23, 23 and 3| of the finished gasket, is stamped from suitable raw sheetrubber of such composition that it will be relatively hard but yieldingwhen vulcanized, the blank being provided with openings 28 and 21'corresponding to the openings 23 and 21 in the finished gasket and athird opening corresponding to the opening 40 in the annular portion 3|of the finished gasket. To the underside of the blank 4|, a circularblank 42 is attached which is made of raw sheet rubber of suchcomposition that it will be relatively soft and flexible whenvulcanized. A reinforcing fabric 31 is embedded in the blank 42 as shownin Fig. 7. A third blank 43, which is annular in shape and which isstamped from raw sheet rubber similar to that of the blank 4| and whichis of less thickness than the material of that blank, is attached asindicated in Figs.- 6 and 7 to the upper side of the blank 4| and to theupper face of the blank 42, the blank 4| being disposed between theblank 43 and blank 42 as indicated in Fig. 7. The composite blank thusassembled is placed in a mold so that a projection 44 in the mold 45extends through the opening 21, it being understood that the mold 45 isof the proper shape to produce the desired flnished gasket structure asshown in Fig. 4.

The upper half of the mold, not shown, is then placed in registry withthe mold section 45 and.

the mold sections are then forced together under high pressure, so as toforce the raw rubber into the shape of the finished gasket structure,the excess rubber flowing from the mold through crevices (not shown)provided for that purpose. The mold is then subjected to heat and thetemperature is maintained at substantially 300 degrees F. forapproximately minutes. The finished gasket is then removed from themold.

The distribution of the soft rubber portion of the diaphragm issubstantially as indicated in Fig. 5, and the sealing ribs 34 on theannular portions 28, 29 and 3| and on the marginal portion of thediaphragm portion 32 consist of the rela- -tively hard material.Therefore, the sealing ribs engage the contact face 14 of the casing l2with uniform pressure throughout. During the vulcanizing process thethree blanks of raw material are integrally joined to one another. andconstitute a one piece gasketstructure having annular gasket portionsand a circular diaphragm portion in which a diaphragm of relatively softrubber is provided surrounded by a marginal portion of relatively hardrubber.

While I have disclosed but one embodiment of the invention and but onemethod of manufacture, it is obvious that changes may be made in thestructure, and in the method of manufacture without departing from thespirit of the invention.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

The combination with a pair of cooperating metal members having engagingsurfaces adapted to be held in metal to metal contact, one of which isprovided with a gasket confining groove, of a gasket made ofresilientmaterial mounted in the groove, said gasket having a fiat body portionwhich is of substantially the same width as the groove so as to fitsnugly therein and which is of less thickness than the depth of thegroove,

so as to provide a space between the outer face of the gasket and thecontact surface of the other member into which all displaced material ofthe gasket may flow, the said gasket having on its outer face arelatively narrow sealing rib which normally extends beyond thecontacting surface of the member containing the groove and which isengaged and pressed into the body of the gasket by the contact face ofthe other member when the members are drawn into metal to metalcooperating contact.

ELLIS E. HEWITT.

